JPH10181216A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording material excellent in an image storage stability to oil and plasticizer. SOLUTION: In this heat sensitive recording material, which is prepared by providing a heat sensitive color developing layer on a support, the heat sensitive color developing layer is obtained by accelerating the polymerization reaction of a polymer formable stock in the presence of a polyvalent amine compound under the condition that a dye precursor is dissolved in a solvent made of the polyvalent isocyanate compound-containing polymer formable stock so as to emulsify and disperse the resultant solution in the water so as to include fine composite particles containing a dye precursor compound in a matrix made of polyurea or polyurethane-polyurea resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material containing dye precursor-containing composite fine particles containing a polyvalent amine compound as a polymerization reaction accelerator and having excellent image stability in printing. Related to recording materials.

[0002]

2. Description of the Related Art A number of methods are known for producing polymer microparticles or microcapsules containing an oily liquid as a core substance and containing a wall material made of a polymer. ing. For example,
Edited by Toray Research Center Research and Planning Division: "New development of fine particle polymer as functional material", published by Toray Research Center (1994), edited by Masazumi Koishi, "fine particle design"
Published by the Industrial Research Council (1987), edited by Tamotsu Kondo, "Microcapsules-Functions and Applications", published by the Japan Standards Association (1991).
And other references. The method for producing polymer fine particles can be broadly classified into a polymerization granulation method in which particles are formed in the polymerization process from polymerizable monomers and a dispersion granulation method in which particles are formed from a polymer solution formed into fine droplets. The method for producing microcapsules can also be classified in substantially the same manner as described above.

Utilizing a color development reaction between a dye precursor, a dye precursor, and a color-developing compound that forms a color by contacting the dye precursor with heating, the two color-forming substances are brought into melting contact by heating,
Thermal recording materials for obtaining a color image are widely known. Such heat-sensitive recording materials are relatively inexpensive,
Since recording devices are compact and easy to maintain, they are used in a wide range of fields as recording media for various applications such as facsimile machines, word processors, and various computers. However, conventional thermosensitive recording materials containing solid particles composed of a dye precursor and a color-developing compound have a disadvantage that the color image is easily erased by the influence of oil or a plasticizer.

It is also known to enclose a dye precursor dissolved in oil in a microcapsule in order to solve the above-mentioned drawbacks and to apply it to a heat-sensitive recording material.
No. 4960, Japanese Patent Publication No. 4-37796, Japanese Patent Publication No. 4-37797, and Japanese Patent Publication No. 5-63315. However, the microcapsules containing the oily liquid in which these dye precursors are dissolved are easily broken by pressure, and the oil contained in the microcapsules and the dissolved dye precursor flow out of the microcapsules and come into contact with the developer. There was a problem such as color development.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having excellent image storability to oils and plasticizers.

[0006]

According to the present invention, there is provided a heat-sensitive recording material comprising a heat-sensitive coloring layer provided on a support, wherein the heat-sensitive coloring layer contains a dye in a solvent comprising a polymer-forming raw material containing a polyvalent isocyanate compound. Dissolving the precursor, emulsifying and dispersing the resulting solution in water, obtained by promoting the polymerization reaction of the polymer-forming raw material in the presence of a polyvalent amine compound, a polyurea or a polyurethane-polyurea resin The present invention relates to a heat-sensitive recording material containing composite fine particles containing the dye precursor compound in a base material composed of:

[0007] Further, the present invention provides the above polyamine compound,
It exists in a thermosensitive recording material having a valence of 3 or more.

Further, dicyclohexylmethane-4,4'-diisocyanate is used as the polyvalent isocyanate compound according to the present invention, and the polyvalent amine compound is at least one selected from diethylenetriamine, triethylenetetramine and tris (aminoethyl) amine. In the heat-sensitive recording material using seeds.

Further, the amount of the polyvalent amine compound used in the present invention depends on the heat-sensitive recording material in which 0.05 mol to 1 mol of the polyamine compound is added to 1 mol of the polyvalent isocyanate compound.

Further, the present invention resides in a heat-sensitive recording material wherein the color developing compound of the composite fine particles containing the dye precursor compound is 4,4'-isopropylidene diphenol.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The dye precursor-containing resin composite fine particles of the present invention are prepared by dissolving a dye precursor in a polyvalent isocyanate compound-containing polymer-forming raw material as a solvent to prepare a solution. Is emulsified and dispersed in an aqueous solution containing a hydrophilic protective colloid, and the resulting emulsified dispersion is subjected to a polymerization reaction of the polymer-forming raw material. The dye precursor is contained in a base material composed of polyurea or polyurethane-polyurea resin. The composite fine particles have high physical strength because they contain substantially no organic solvent. Therefore, the heat-sensitive recording material using the composite fine particles of the present invention has a heat-sensitive coloring layer excellent in pressure resistance and friction resistance.

The composite fine particles of the present invention comprise a base material comprising at least one polymer substance (resin) selected from polyurea or polyurethane-polyurea, and a dye precursor contained therein. Therefore, it is considered that the dye precursor and the polymer substance are mixed at the molecular level and exist in a solid solution state. In these composite particles,
It does not substantially contain liquids such as oily solvents. The composite fine particles may be solid solids (solid bodies) having no voids, porous solids, or hollow solids having a hollow portion having a diameter of less than half the particle diameter. However, a hollow solid having a large hollow portion is not preferable because it is easily broken by pressure.

In the production of the composite fine particles of the present invention, a solution is prepared by dissolving a dye precursor in a polyvalent isocyanate compound. The weight ratio of the dye precursor compound to the polyvalent isocyanate compound in the production of the composite fine particles is such that the content of the dye precursor compound is 5 to 80% by weight based on the total weight of the composite fine particles from the viewpoint of color development sensitivity. Is preferred, and 2
More preferably, it is 0 to 50% by weight. The melting temperature at this time is preferably from 40 to 160 ° C, more preferably from 60 to 120 ° C. At a temperature of 40 ° C. or lower, the solubility of the solute dye precursor in the polyvalent isocyanate compound is low, and it is impossible to produce composite fine particles having sufficient separability. On the other hand, if the dissolution temperature exceeds 160 ° C., the thermal decomposition of the dye precursor proceeds, and the composite fine particles may not be produced stably. This solution is emulsified and dispersed in an aqueous medium in which a protective colloid substance such as polyvinyl alcohol is dissolved and contained. The emulsified dispersion is heated to 40 ° C. or higher to polymerize the polymer-forming raw material to form composite fine particles comprising a base material composed of polyurea or polyurethane-polyurea resin and a dye precursor contained in the base material. I do.

To polymerize the polymer-forming raw material, the dispersion is heated to 60 ° C. to 95 ° C., and the temperature is maintained at this temperature for 3 hours or more, more preferably 5 hours or more, to produce composite fine particles. it can. In the step of polymerizing the polymer-forming raw material, a polyvalent amine compound is made to react with the polymer-forming material. The composite fine particles thus obtained are
A heat-sensitive recording material having excellent image stability against oil and plasticizer can be provided.

As the dye precursor which can be contained in the composite fine particles used in the present invention, a leuco compound such as a triaryl compound, a diphenylmethane compound, a thiazine compound, a spiro compound, a lactam compound or a fluoran compound can be preferably used. These dye precursors each give a unique color tone upon contact with a color developer, and the color tone is black,
It ranges from red, magenta, orange, blue, green, and yellow.

As the dye precursor giving black color, 3
-Pyrrolidino-6-methyl-7-anilinofluoran,
3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3- (N-isoamyl-N-ethylamino) -7- (o-chloroanilino) fluoran,
3- (N-ethyl-p-toluidino) -6-methyl-7
-Anilinofluoran, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7
-Anilinofluoran, 3-di-n-butylamino-6
-Methyl-7-anilinofluoran, 3-di-n-amylamino-6-methyl-7-anilinofluoran, 3-
(N-isoamyl-N-ethylamino) -6-methyl-
7-anilinofluoran, 3- (Nn-hexyl-N
-Ethylamino) -6-methyl-7-anilinofluoran, 3- [N- (3-ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluoran, 3-
[N- (3-ethoxypropyl) -N-methylamino)
-6-methyl-7-anilinofluoran, 3-diethylamino-7- (2-chloroanilino) fluoran, 3-
Di-n-butylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7
-(2,6-dimethylanilino) fluoran, 3-diethylamino-6-methyl-7- (2,4-dimethylanilino) fluoran, 2,4-dimethyl-6- (4-dimethylaminoanilino) fluoran , And 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-
Anilino fluoran or the like can be used.

In the present invention, among the dye precursors giving a black color, 3-di-n-amylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl which are excellent in light resistance are used. -7- (2,6-dimethylanilino) fluoran, 3-diethylamino-6-methyl-7- (2,4-dimethylanilino) fluoran, 2,
It is preferably one kind selected from 4-dimethyl-6- (4-dimethylaminoanilino) fluoran.

Dye precursors giving a red, magenta, or orange color development include 3,6-bis (diethylamino) fluoran-γ-anilinolactam and 3,6-bis (diethylamino) fluoran-γ- ( p-nitro)
Anilinolactam, 3,6-bis (diethylamino) fluoran-γ- (o-chloro) anilinolactam, 3-
Dimethylamino-7-bromofluorane, 3-diethylaminofluoran, 3-diethylamino-6-methylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-chlorofluoran, 3-
Diethylamino-7-bromofluorane, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-6,8-dimethylfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino- 7-tert-butylfluoran, 3- (N-ethyl-N-tolylamino) -7-methylfluoran, 3
-(N-ethyl-N-tolylamino) -7-ethylfluoran, 3- (N-ethyl-N-isobutylamino)-
6-methyl-7-chlorofluoran, and 3- (N-
Ethyl-N-isoamylamino) -7,8-benzofluoran.

Dye precursors that provide red, magenta and orange color tones are further exemplified by 3-cyclohexylamino-6-chlorofluoran and 3-di-n-butylamino-6-methyl-7-bromo. Fluoran, 3-di-
n-butylamino-7,8-benzofluoran, 3-tolylamino-7-methylfluorane, 3-tolylamino-7-ethylfluoran, 2- (N-acetylanilino) -3-methyl-6-di -N-butylaminofluoran, 2- (N-propionylanilino) -3-methyl-
6-di-n-butylaminofluoran, 2- (N-benzoylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-carbobutoxyanilino)
-3-methyl-6-di-n-butylaminofluoran,
2- (N-formylanilino) -3-methyl-6-di-
n-butylaminofluoran, 2- (N-benzylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-allylanilino) -3-methyl-6
Di-n-butylaminofluoran and 2- (N-methylanilino) -3-methyl-6-di-n-butylaminofluoran.

As a dye precursor exhibiting red, magenta and orange color tone, 3,3'-bis (1-n-butyl-2-methylindol-3-yl)
Phthalide, 3,3'-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3'-bis (1-
n-octyl-2-methylindol-3-yl) phthalide, 7- (N-ethyl-N-isoamylamino) -3
-Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide], 7- (N-ethyl-N-isoamylamino) -3
-Methyl-1-p-methylphenylspiro [(1,4-
Dihydrochromeno [2,3-c] pyrazole) -4,
3'-phthalide], and 7- (N-ethyl-Nn-
Hexylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide].

When 3-diethylamino-7-chlorofluorane or 3-diethylamino-6-methyl-7-chlorofluorane is used as a red dye precursor,
For color tone correction, it is desirable to use a mixture of dyes having different color tones, for example, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide or 3,3'-bis By blending a dye precursor that develops a red-purple color tone such as (1-ethyl-2-methylindol-3-yl) phthalide, a color tone with a stronger reddish tint can be obtained.

As the dye precursor giving a blue color,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3 -(1-ethyl-2
-Methylindol-3-yl) -3- (2-methyl-
4-diethylaminophenyl) -4-azaphthalide, 3
-(1-ethyl-2-methylindol-3-yl)-
3- (2-ethoxy-4-diethylaminophenyl)-
4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-
4-diethylaminophenyl) -4-azaphthalide, 3-diphenylamino-6-diphenylaminofluoran, and the like.

As the dye precursor giving green color, 3
-(N-ethyl-NN-hexylamino) -7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4 -Azaphthalide, 3-
(N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluoran, 3- [p-
(P-anilinoanilino) anilino] -6-methyl-7
-Chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, and the like.

Dye precursors that give yellowish color development include 3,6-dimethoxyfluoran and 1- (4-
n-dodecyloxy-3-methoxyphenyl) -2-
(2-quinolyl) ethylene and the like. The above dye precursor may be used alone, but may be used in combination with a dye precursor of another color for color tone correction.

The polyvalent isocyanate compound used in the present invention forms a urea bond by reacting with an amino compound in addition to water, and forms a urethane bond by reacting with a hydroxy compound to polymerize. The polymer formed is
Polyurea, or polyurethane-polyurea,
The polymer-forming material used may be only a polyvalent isocyanate compound, or a mixture of a polyvalent isocyanate compound and a polyol that reacts with the polyisocyanate compound, or a polyol adduct of a polyvalent isocyanate compound,
It may be a multimer such as a biuret form or an isocyanurate form. A dye precursor is dissolved in these polyvalent isocyanate compounds, and this solution is emulsified and dispersed in an aqueous medium containing a protective colloid substance such as polyvinyl alcohol or a surfactant in the presence of a polyvalent amine compound. It is obtained by accelerating the polymerization reaction of the polymer-forming raw material to obtain a polymer. Thereby, composite fine particles composed of the dye precursor and the polymer substance can be formed.

Examples of the polyvalent isocyanate compound used as the polymer-forming raw material include m-phenylene diisocyanate, p-phenylene diisocyanate,
2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, 4,4'-diphenylmethane diisocyanate,
Polymeric diphenylmethane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 5
-Isocyanate-1- (isocyanatomethyl)-
1,3,3-trimethylcyclohexane, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4 '
-Diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate,
Propylene-1,2-diisocyanate, butylene-
1,2-diisocyanate, cyclohexylene-1,2
Diisocyanates such as diisocyanate and cyclohexylene-1,4-diisocyanate, 4,4 ', 4 "
-Triphenylmethane triisocyanate, toluene-
Triisocyanates such as 2,4,6-triisocyanate, 4,4'-dimethyldiphenylmethane-2,
And tetraisocyanates such as 2 ', 5,5'-tetraisocyanate. Examples of the adduct of a polyvalent isocyanate and a polyol include trimethylolpropane adduct of hexamethylene diisocyanate and 2,4
-Isocyanate prepolymers such as trimethylolpropane adduct of tolylene diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, and hexanetriol adduct of tolylene diisocyanate can be used. In addition, these polyvalent isocyanate compounds, for example, a biuret of hexamethylene diisocyanate, an isocyanurate of hexamethylene diisocyanate, and the like can also be preferably used as the polymer-forming raw material of the present invention.

In the present invention, it is particularly desirable to use dicyclohexylmethane-4,4'-diisocyanate having low viscosity and good workability. Of course, it can be used in combination with other polyvalent isocyanates.

As the polyol compound used for the polymer-forming raw material, for example, ethylene glycol, 1,3-
Propanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,7
-Heptanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,
2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol,
2,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-
Cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,6-trihydroxyhexane, phenylethylene glycol, 1,1,
Aliphatic polyols such as 1-trimethylolpropane, hexanetriol, pentaerythritol and glycerin, 1,4-di (2-hydroxyethoxy) benzene,
Condensation product of an aromatic polyhydric alcohol such as 1,3-bis (2-hydroxyethoxy) benzene and an alkylene oxide, p-xylylene glycol, m-xylylene glycol, α, α′-dihydroxy-p-diisopropyl Benzene, 4,4'-dihydroxydiphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl)
Benzyl alcohol, 4,4'-isopropylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide,
Examples include ethylene oxide adducts of 4,4'-isopropylidene diphenol, propylene oxide adducts of 4,4'-isopropylidene diphenol, and acrylates having a hydroxyl group in the molecule such as 2-hydroxyacrylate. it can.

The polyvalent isocyanate compound, the polyol compound and the like are not limited to the above compounds, and two or more kinds may be used in combination as needed.

Examples of the polyvalent amine compound used in the present invention include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, piperazine and 2-methylpiperazine. , 2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, tris (aminoethyl) amine, amine adducts of epoxy compounds, and the like. Can be In addition, it is more preferable to use an aliphatic polyamine compound from the viewpoint that the light resistance is not reduced.

In the present invention, diamine triamine, triethylene tetramine,
When composite fine particles obtained by accelerating the polymerization reaction of the polymer-forming raw material in the presence of tris (aminoethyl) amine are used as a heat-sensitive recording material, the effect of improving image stability against oil and plasticizer is improved. Is preferred. It is desirable to use at least one selected from these compounds as a polyvalent amine compound. Two or more polyamine compounds used in the present invention may be used in combination.

The characteristics of the composite fine particles can be changed depending on the type and amount of the polyamine compound. The addition amount of the polyamine compound is preferably 0.05 to 1 mol of the polyamine compound per 1 mol of the polyisocyanate compound.
If the amount is less than 0.05 mol, the effect on image stability is not great, and if it is more than 1 mol, unreacted polyvalent amine remains in the system, or there is a problem such as yellowing during storage, which is not preferable.

Further, within a range that does not impair the object of the present invention,
You may use together a tin compound, a polyamide compound, an epoxy compound, etc.

In the present invention, as an emulsifier (protective colloid agent) used for preparing the composite fine particles, modified polyvinyl alcohol such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and sulfone group-modified polyvinyl alcohol; methyl cellulose; carboxymethyl cellulose; Water-soluble synthetic high molecular compounds such as maleic anhydride copolymer salts and derivatives thereof can be used. A surfactant, an antifoaming agent and the like may be used together with such an emulsifier. The amount of the emulsifier used in the preparation of the composite fine particles is not particularly limited. However, it is preferable to use 1 to 200% by weight of the emulsifier based on the weight of the generally obtained composite fine particles, and more preferably 3 to 150% by weight. preferable.

The color-developing compound used in the heat-sensitive recording material of the present invention is not particularly limited, but generally has the property of being liquefied or dissolved by an increase in temperature, and is contacted with the above-mentioned dye precursor to form it. It is selected from those having a color developing property. A typical color developing compound is 4-t
tert-butylphenol, 4-acetylphenol,
4-tert-octylphenol, 4,4'-sec
-Butylidene diphenol, 4-phenylphenol,
4,4'-dihydroxydiphenylmethane, 4,4'-
Isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (3
-Methyl-6-tert-butylphenol), 4,
4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4 '
-Isopropoxydiphenyl sulfone, and bis (3
Phenolic compounds such as (allyl-4-hydroxyphenyl) sulfone.

Further, in the present invention, compounds which can be used as the color developing compound include 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate,
Phenolic compounds such as 4-sec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, and 4,4'-dihydroxydiphenyl ether Or benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, Aromatic carboxylic acids such as 3,5-di-tert-butylsalicylic acid, and phenolic compounds, and organic acidic substances such as salts of aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum and calcium. But That.

When 4,4'-isopropylidenediphenol is used as the color developing compound used in the heat-sensitive recording material of the present invention, solid particles of the dye precursor and 4,4'-isopropylidene as the color developing compound are used. Compared to a conventional heat-sensitive recording material containing dendiphenol, the effect of improving image stability with respect to oil and plasticizer is high, and the value of industrial use is high, which is preferable.

Usually, the color developing compound is preferably used in an amount of 30 to 300 parts by weight, more preferably 50 to 200 parts by weight, based on 100 parts by weight of the composite fine particles. Of course, if necessary, two or more types of color developing compounds can be used in combination.

In the present invention, an image stabilizer may be used mainly for improving the storability of the color recording image. Examples of such an image stabilizer include 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane and 1,1,3-tris (2-methyl-
4-hydroxy-5-tert-butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-
tert-butylphenyl) butane, 4,4 ′-[1,
Phenolic compounds such as 4-phenylenebis (1-methylethylidene)] bisphenol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol; 4-benzyloxyphenyl-4'
-(2-methyl-2,3-epoxypropyloxy) phenylsulfone, 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, and 4- (2-ethyl-1,2-epoxyethyl) diphenyl Epoxy compounds such as sulfones, and those containing at least one selected from isocyanuric acid compounds such as 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid Can be used. Of course, the image stabilizer is not limited to these, and two or more compounds can be used in combination as needed.

In the present invention, a sensitizer can be used to improve the heat-sensitive recording color development sensitivity. As the sensitizer, a compound conventionally known as a sensitizer for a thermosensitive recording material can be used. For example, parabenzyl biphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate can be used. ,
Di-o-chlorobenzyl adipate, 1,2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-oxalate
Examples thereof include p-chlorobenzyl, 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, metaterphenyl, diphenyl, and benzophenone. Among these compounds, di-p-methylbenzyl oxalate and di-p-oxalate
When chlorobenzyl is used as a sensitizer, a sensitizing effect with less fogging can be obtained.

The color developing compound used in the present invention,
Additives such as an image stabilizer and a sensitizer may be dispersed in water in the same manner as when the dye precursor is used in the form of solid fine particles, and may be mixed with the heat-sensitive coloring layer-forming paint when preparing the coating. . Further, these additives may be dissolved in a solvent, and the resulting solution may be emulsified in water using a water-soluble polymer compound as an emulsifier. Further, the image stabilizer and the sensitizer may be contained in the composite fine particles containing the dye precursor.

In the present invention, a fine pigment having a high whiteness and an average particle diameter of 10 μm or less can be contained in the thermosensitive coloring layer in order to improve the whiteness of the thermosensitive coloring layer and the uniformity of the image. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated calcium carbonate and silica Inorganic pigments and organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin and polystyrene resin can be used. Oil absorption is 50ml / 1 to prevent sticking to the thermal head and sticking.
It is preferred to use more than 00 g of pigment. The amount of the pigment is preferably such that the coloring density is not reduced, that is, 50% by weight or less based on the total solid weight of the thermosensitive coloring layer.

In the present invention, an adhesive is used as another material constituting the heat-sensitive coloring layer.
Crosslinking agents, waxes, metal soaps, colored dyes, colored pigments,
And a fluorescent dye. Examples of the adhesive include polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, and acrylamide-acrylic acid ester. Coalescence, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer,
Isobutylene-maleic anhydride copolymer, casein, water-soluble polymer materials such as gelatin and derivatives thereof, and polyvinyl acetate, polyurethane, polyacrylic acid,
Emulsions such as polyacrylates, vinyl chloride-vinyl acetate copolymers, polybutyl methacrylate, ethylene-vinyl acetate copolymers, and water-insoluble polymers such as styrene-butadiene copolymers and styrene-butadiene-acrylic copolymers Examples include coalesced latex.

Further, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive can be contained in the thermosensitive coloring layer. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, and ammonium persulfate and ferric chloride, and chloride Magnesium, sodium tetraborate, potassium tetraborate or other inorganic compound or at least one crosslinkable compound selected from boric acid, boric acid triester, boron-based polymer, etc., 100 parts by weight of the total solid content of the thermosensitive coloring layer Is preferably used in the range of 1 to 10 parts by weight.

The wax added to the thermosensitive coloring layer includes paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax,
And waxes such as polyethylene wax, and higher fatty acid amides such as stearic acid amide and ethylenebisstearic acid amide, higher fatty acid esters,
And derivatives thereof. In particular, when a methylolated fatty acid amide is added to the thermosensitive coloring layer, a sensitizing effect can be obtained without deteriorating the background fog.

As the metal soap added to the thermosensitive coloring layer, higher fatty acid polyvalent metal salts such as zinc stearate,
Aluminum stearate, calcium stearate,
And zinc oleate. When a multi-color heat-sensitive recording material is used, the inclusion of a color dye and a color pigment having a color tone that is complementary to the low-temperature color tone in the heat-sensitive coloring layer adjusts the color tone of the blank portion of the recording material. It is preferable to Further, if necessary, various additives such as an oil repellent, an antifoaming agent, and a viscosity modifier can be added to the thermosensitive coloring layer as long as the effects of the present invention are not impaired. The thermosensitive coloring layer is coated on the support so that the coating amount after drying is ² to 20 g / m ² , more preferably 4 to 10 g / m ² .

In the present invention, a protective layer as used in a conventionally known thermosensitive recording material can be provided on the thermosensitive coloring layer. Such a protective layer usually contains a water-soluble polymer material and a pigment. As the water-soluble polymer material and the pigment, the materials exemplified as the components of the thermosensitive coloring layer can be used. At this time, it is more preferable to add a crosslinking agent to impart water resistance to the protective layer. Further, a resin layer cured by an electron beam or a resin layer cured by an ultraviolet ray can be provided. The protective layer mainly composed of a resin cured by an electron beam or ultraviolet rays is more preferably provided on a protective layer containing a water-soluble polymer material and a pigment. The protective layer, the coating amount after drying 0.5 to 10 g / m ^2, more preferably coated on a support so as 1 to 5 g / m ^2.

The heat-sensitive recording material of the present invention can be printed with UV ink, flexo ink or the like. in this case,
The printing may be performed on any layer such as a thermosensitive layer, a protective layer, an electron beam curable resin layer, or an ultraviolet curable resin layer.

There is no particular limitation on the type, shape, dimensions, etc. of the support material used in the present invention, and examples thereof include high quality paper (acid paper, neutral paper), medium paper, coated paper, art paper, and cast paper. In addition to coated paper, glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, nonwoven fabric, synthetic resin film, and the like, various transparent supports and the like can be appropriately selected and used.

In the present invention, an undercoat layer used in a conventionally known heat-sensitive recording material can also be used. In particular, when paper is used as the support, it is preferable to provide an undercoat layer. By using a pigment having a high porosity such as silica or calcined kaolin for the undercoat layer, the coloring sensitivity of the thermosensitive coloring layer thereon can be increased. Including a plastic pigment, hollow particles, foam, or the like in the undercoat layer is also effective in improving the color sensitivity of the thermosensitive coloring layer formed thereon.

The method for forming each of the above layers on the support includes known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method. Either may be used. Further, it is also possible to suppress the penetration of oil or plasticizer from the back surface of the recording material, or to provide a back layer for curl control on the back surface of the support. Smoothing the heat-sensitive coloring layer using a known smoothing method such as a super calendar or a soft calendar is effective in increasing the coloring sensitivity. The surface of the thermosensitive coloring layer may be treated by applying it to either a metal roll or an elastic roll of a calender.

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Unless otherwise specified, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Example 1 (1) Preparation of Support Canadian Standard Freeness (CSF) 480
100 parts of hardwood bleached kraft pulp beaten ml, from 10 parts of talc, petroleum resin sizing agent 0.3 parts, form regulating the paper stock obtained by adding 0.5 parts of aluminum sulfate, the basis weight 64 g / m ² Paper was made. The base paper was coated with a 2% solution of polyvinyl alcohol by a size press. The coating amount was 0.8 g / m ² (dry). Oken type smoothness (J.TAPPI No.5) is 50 on machine calendar
A smoothing treatment was performed so that the time became seconds to obtain a support used in the present invention.

(2) Formation of Undercoat Layer Silica (Mizukasil P527, oil absorption 190
30 parts of 0.1 ml / 100 g, manufactured by Mizusawa Chemical Industry Co., Ltd.
It was dispersed in 70 parts of 7% sodium polyacrylate with a Cowles disperser. Separately, polyvinyl alcohol having a solid content of 10% (NM11Q, Nippon Synthetic Chemical Industry Co., Ltd.)
Aqueous solution was prepared. The pigment silica dispersion and the adhesive liquid are blended so that the blending ratio of solids is 85:15,
This paint was applied to one side of the support using a Meyer bar at 7.0.
g / m ² (dry) was applied to form an undercoat layer.

(3) Preparation of Black Fine Particle Dye Precursor Containing Composite Fine Particle Dispersion 5-Di-n-amylamino-6-methyl-7-anilinofluoran 5 parts as a black color forming dye precursor at 120 ° C.
Was dissolved in 15 parts of dicyclohexylmethane-4,4'-diisocyanate heated to 35 ° C., and the solution was cooled to 35 ° C., and then 20% sulfone group-modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Goselan L-32)
66) The mixture was gradually added to 100 parts of an aqueous solution, and emulsified and dispersed by stirring with a homogenizer at a rotation speed of 12000 rpm. Then, an aqueous solution in which 4 parts of diethylenetriamine as a polyvalent amine compound was dissolved in 50 parts of water was added to the emulsified dispersion. Homogenized. This emulsified dispersion was heated to 90 ° C.
A polymerization reaction was carried out for 10 hours to prepare a composite fine particle dispersion containing a black color-forming dye precursor having an average particle diameter of 0.4 μm.

(4) Thermosensitive recording material Color-developing compound: 40 parts of 4,4′-isopropylidene diphenol, 10% polymerization degree of polyvinyl alcohol 500,
(Saponification degree: 90%) 40 parts of an aqueous solution and 20 parts of water were mixed, pulverized and dispersed using a vertical sand mill (sand grinder, manufactured by Imex Co., Ltd.) so that the average particle diameter became 1.2 μm. Silica (Mizukasil P52) as a pigment
7. Oil absorption 190ml / 100g, Mizusawa Chemical Industry Co., Ltd.
Was dispersed in 70 parts of 0.7% sodium polyacrylate with a Cowles disperser. Separately, an aqueous solution of polyvinyl alcohol (NM11Q, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a solid content of 10% is used as an adhesive liquid, and an aqueous dispersion of zinc stearate having a solid content of 21% (Z
-7, Chukyo Yushi Co., Ltd.). The thermosensitive coloring layer paint mixed and prepared at the following mixing ratio (solid content) is applied on the previously formed undercoat layer at a coating amount (dry) of 5.0 g / m ² and dried to dry the thermosensitive coloring layer. Was formed. The obtained coated paper was subjected to a smoothing treatment by a super calender so that the surface of the heat-sensitive coloring layer had a surface smoothness of Oken type of 1000 seconds to obtain a heat-sensitive recording material. Component Amount (parts by weight) Composite fine particle dispersion containing black color-forming dye precursor 40 Color developing component dispersion 40 Pigment dispersion 15 Lubricant dispersion 5

Example 2 A thermosensitive recording material was produced in the same manner as in Example 1 except that triethylenetetramine was used as a polyvalent amine compound, and composite fine particles containing a black color-forming dye precursor were prepared.

Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that tris (aminoethyl) amine was used as a polyvalent amine compound, and composite fine particles containing a black color-forming dye precursor were prepared.

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that composite fine particles containing a black chromogenic dye precursor were prepared without adding a polyvalent amine compound.

Comparative Example 2 Black color-forming dye precursor; 3-di-n-amylamino-6
-Methyl-7-anilinofluorane (40 parts), 10% polyvinyl alcohol (polymerization degree: 500, saponification degree: 90%) aqueous solution (40 parts) and water (20 parts) were mixed, and a vertical sand mill (manufactured by Imex Co., Ltd., sand grinder) ), And pulverized and dispersed such that the average particle diameter becomes 1.2 μm. Developing compound: 4,4'-isopropylidene diphenol 40 parts, 10% polyvinyl alcohol polymerization degree 500,
(Saponification degree: 90%) 40 parts of an aqueous solution and 20 parts of water were mixed, pulverized and dispersed using a vertical sand mill (sand grinder, manufactured by Imex Co., Ltd.) so that the average particle diameter became 1.2 μm. Silica (Mizukasil P52) as a pigment
7. Oil absorption 190ml / 100g, Mizusawa Chemical Industry Co., Ltd.
Was dispersed in 70 parts of 0.7% sodium polyacrylate with a Cowles disperser. Separately, an aqueous solution of polyvinyl alcohol (NM11Q, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a solid content of 10% is used as an adhesive liquid, and an aqueous dispersion of zinc stearate having a solid content of 21% (Z
-7, Chukyo Yushi Co., Ltd.). The thermosensitive coloring layer paint mixed and prepared at the following mixing ratio (solid content) is applied on the previously formed undercoat layer at a coating amount (dry) of 5.0 g / m ² and dried to dry the thermosensitive coloring layer. Was formed. The obtained coated paper was subjected to a smoothing treatment by a super calender so that the surface of the heat-sensitive coloring layer had a surface smoothness of Oken type of 1000 seconds to obtain a heat-sensitive recording material. Component Amount (parts by weight) Black color-forming dye precursor dispersion 10 Color-developing compound dispersion 40 Pigment dispersion 30 Adhesive liquid 15 Lubricant dispersion 5

A test was performed on each of the heat-sensitive recording materials of Examples 1 to 3 and Comparative Examples 1 and 2. Thermal recording was performed using a thermal printing tester TH-PMD (manufactured by Okura Electric Co., Ltd.).
Solid printing of 256 lines was performed under the conditions of line recording time: 4 msec, sub-scanning line density: 8 lines / mm, and applied energy per dot: 2.0 mJ.

The color product thus obtained is
The recorded image density was measured. The recorded image density and the image density after the storability treatment were obtained by measuring the recorded image portion of the recorded sample with a Macbeth densitometer (manufactured by Macbeth, model number: RD-914). Oil resistance and plasticizer resistance were evaluated by the following methods.
Oil resistance was measured by adding a recorded sample to salad oil at 20 ° C for 12 hours.
After soaking for a period of time, the recorded image area was measured with a Macbeth densitometer and evaluated by the preservation ratio (%) = ((concentration after soaking) / (density before soaking) × 100). If the preservation rate is 50% or more, it is a readable level, and there is no practical problem. The plasticizer resistance was measured by sandwiching the recorded sample between polyvinyl chloride films (Hi-wrap KMA-W, manufactured by Mitsui Toatsu Co., Ltd.) at 20 ° C.
After 24 hours, the recorded image area was measured with a Macbeth densitometer and evaluated by the preservation ratio (%) = ((density after processing) / (density before processing) × 100). If the preservation rate is 50% or more, it is a readable level, and there is no practical problem. Table 1 shows the test results.

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[Table 1]

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As is clear from the results shown in Table 1, the present invention makes it possible to produce a heat-sensitive recording material having excellent image stability after printing.

Claims (5)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer provided on a support, wherein the thermosensitive coloring layer is obtained by dissolving a dye precursor in a solvent comprising a polyvalent isocyanate compound-containing polymer-forming material. The obtained solution is emulsified and dispersed in water, and is obtained by accelerating the polymerization reaction of the polymer-forming raw material in the presence of a polyvalent amine compound, and a base material composed of polyurea or polyurethane-polyurea resin, A heat-sensitive recording material comprising composite fine particles containing a dye precursor compound. 2. The heat-sensitive recording material according to claim 1, wherein the polyvalent amine compound has three or more valences. 3. A method according to claim 1, wherein dicyclohexylmethane-4,4'-diisocyanate is used as the polyvalent isocyanate compound, and at least one selected from diethylenetriamine, triethylenetetramine and tris (aminoethyl) amine is used as the polyvalent amine compound. Item 2. The heat-sensitive recording material according to Item 1. 4. A polyvalent isocyanate compound per mole,
4. The heat-sensitive recording material according to claim 1, wherein 0.05 to 1 mol of the polyamine compound is added. 5. The heat-sensitive recording material according to claim 1, wherein the color developing compound of the composite fine particles containing the dye precursor compound is 4,4′-isopropylidene diphenol.